Identify additional Spring Boot scenarios

Continue fleshing out the `azure.springboot` roadmap after the initial scenarios are complete. Start with the areas we intentionally deferred:

- Azure Kubernetes Service
- Private networking
- Spring Boot native images with GraalVM

Use customer feedback, preview usage, and current Spring Boot and Java on Azure guidance to identify other scenarios worth considering. For each one, decide whether to add it to the roadmap, cover it through an existing issue, assign it to another extension, or explicitly defer it.

Create follow-up issues only when there is a clear customer need and the work can be scoped to `azure.springboot`.

## Boundaries

- This is a planning issue. Do not implement the scenarios here.
- Do not add Spring-specific commands or verbs.
- Do not modify azd core.
- Core or extension-framework dependencies belong in their owning epics.
- New implementation work must remain scoped to `cli/azd/extensions/azure.springboot/` and extension-specific repository plumbing.

Start by reviewing the existing azure.springboot roadmap and the three deferred areas, then compare customer feedback, preview usage, and current Spring Boot and Java on Azure guidance. Use cli/azd/extensions/azure.springboot/ and extension-specific repository plumbing to scope candidates. Done means each scenario is added, mapped to an existing issue or extension, or explicitly deferred, with follow-up issues only for clearly scoped customer needs.

Written by the indexing model from the issue text.